Radiographic imaging such as x-ray imaging has been used for years in medical applications and for non-destructive testing.
Normally, an x-ray imaging system includes an x-ray source and an x-ray detector array consisting of multiple detectors comprising one or many detector elements (independent means of measuring x-ray intensity/fluence). The x-ray source emits x-rays, which pass through a subject or object to be imaged and are then registered by the detector array. Since some materials absorb a larger fraction of the x-rays than others, an image is formed of the subject or object.
An example of a commonly used x-ray imaging system is an x-ray Computed Tomography (CT) system, which may include an x-ray tube that produces a fan- or cone beam of x-rays and an opposing array of x-ray detectors measuring the fraction of x-rays that are transmitted through a patient or object. The x-ray tube and detector array are mounted in a gantry that rotates around the imaged object.
X-ray detectors made from low-Z materials such as Silicon need to have a substantial thickness in the direction of the x-ray beam in order to have sufficient detection efficiency to be used in CT. This can be solved by, for example, using an “edge-on” geometry, as in reference [1], in which the detector array is built up of a multitude of detectors, which comprise thin wafers of a low-atomic number material, oriented with the edge towards the impinging x-rays.
Examples of x-ray detectors with a low Z material such as Silicon can be found in references [1] and [2].
There is a general challenge in achieving a high detection efficiency, which translates into having a high fill factor and a high absorption efficiency (length in the direction of the impinging x-rays).